Self-Assembled Artificial Water Channels—Structural Determinants of for Enhanced Membranes Filtration Performances

Artificial water channels-AWC and their natural aquaporin counterparts are selectively transport water. They are a tremendous source of inspiration to construct biomimetic membrane technologies, including desalination. These biomimetic membranes contain variable nanochannel constructs with adaptative architectures and morphologies. Herein, we critically discuss the structural details that can impact on performances of biomimetic I-quartets AWCs obtained <i>via</i> adaptive self-assembly of alkylureido-ethyl-imidazoles <b>HC4</b>-<b>HC18</b> in bilayer or polymeric desalination membranes. We first revisit I-quartet performances and transport behaviors in bilayer membranes, identifying that hydrophobicity is an essential key parameter to increase water permeability. We compare various channel types with different hydrophobic tails (from <b>HC4</b> to <b>HC18</b>) and we found in particular that a huge increase in single channel water permeability from 10⁴to 10⁷water molecules/s/ channel is obtained by increasing the size of grafted alkyl tail. Quantitative assessment of biomimetic AWC-polyamide membranes formats show that pure water permeability increases from roughly 2.09 to 3.85 L m⁻²h⁻¹bar⁻¹, for <b>HC4</b> and <b>HC6</b> membranes while maintaining higher salt rejection (99.25-99.51%) while the <b>HC8</b> loading induce a drop of performance reminiscent with a defective membrane formation. We show that the production of nanoscale defects can be obtained with insoluble low soluble and low dispersed particles of AWCs, explaining observed subpar performance. We conclude that optimal solubility enabling breakthrough performance, must be considered to maximize the inclusion and the stability in the bilayer membranes or to find an optimal homogeneous distribution of percolated particles that minimize the defects in hybrid polyamide membranes.<br/><br/>[1] M. Di Vincenzo, A. Tiraferri, V.-E. Musteata, S.Chisca, R.Sougrat, L.-B. Huang, S. P. Nunes, M. Barboiu, <i>Nature </i><i>Nanotechnol.</i> <b>2021</b>, 16, 190-196.<br/>[2] M. Di Vincenzo, et al. <i>Proc. Natl. Acad. Sci. USA,</i> <b>2021</b>, <i>118(37)</i>, e2022200118<br/>[3] L.-B. Huang, M. Di Vincenzo, M. Göktuğ Ahunbay, A. van der Lee, D. Cot, S. Cerneaux, G. Maurin, and M. Barboiu, <i>J. Am. </i><i>Chem. Soc.</i> 2021, <i>143</i>, 14386-14393.